Rearrange the following phrases into a meaningful sentence. The beginning of the sentence has been given below. Read the options and find out which of the four combinations is correct:-

The need for a scientific understanding...

(A) the Rio Earth Summit, the first of its kind
(B) involving world leaders on environment and development
(C) of natural ecosystems including forests was the main objective of
(D) of phenomena like climate change, biodiversity, and conservation

Choose the correct answer from the options given below.

(D), (C), (A), (B)

The correct answer is Option (3) → (D), (C), (A), (B)

(D) of phenomena like climate change, biodiversity, and conservation
(C) of natural ecosystems including forests was the main objective of
(A) the Rio Earth Summit, the first of its kind
(B) involving world leaders on environment and development

The need for a scientific understanding of phenomena like climate change, biodiversity, and conservation, of natural ecosystems including forests was the main objective of the Rio Earth Summit, the first of its kind, involving world leaders on environment and development.